Thermoplastic compositions with nonlinear optical activity

ABSTRACT

This invention provides thermoplastic polymeric materials comprising polycarbonate and polyestercarbonate resins and oriented polymeric compositions thereof which exhibit nonlinear optical properties.

FIELD OF THE INVENTION

The present invention relates to the use of thermoplastic polymericmaterials for the preparation of novel nonlinear optical (NLO) materialswhich can be useful in nonlinear optical devices. More particularly, thepresent invention relates to NLO media incorporating polycarbonate andpolyestercarbonate resins.

BACKGROUND OF THE INVENTION

Information may be more rapidly processed and transmitted using opticalas opposed to electrical signals. Optical signals can be used to enhancethe performance of electronics processors. For example, electronic wiresinterconnecting integrated circuits (ICs) can be replaced with opticalinterconnects and the . information processed with IC drivenelectro-optic modulators. Optical signals in fiber optic communicationscan be encoded on the optical carrier using electro-optic (EO)modulators. In both of the processes above, nonlinear optical materialswith second-order nonlinear optical activity are necessary to affect themodulation of light signal.

Nonlinear optical materials can also be used for frequency conversion oflaser light. Such a conversion is desirable in many applications. Forexample, optical memory media are presently read using 830 nm light fromdiode lasers. The 830 nm light wavelength limits the spot sizes whichcan be read and hence the density of data stored on the optical memorymedia. Similarly, in fiber optic communications, light wavelengths of1.3 μm or 1.5 pm are desirable due to the low transmission losses ofglass fiber at those wavelengths. However, those wavelengths are toolong for detection by Si based detectors. It is desirable to frequencydouble the 1.3 pm or 1.5 μm wavelengths to 650 nm or 750 nm wavelengthswhere Si based detectors could be used.

Nonlinear optical materials which have been used in electro-opticdevices have in general been inorganic single crystals such as lithiumniobate (LiNbO₃) or potassium dihydrogen phosphate (KDP). More recently,nonlinear optical materials based on organic molecules, and inparticular polar aromatic organic molecules have been developed.

The nonlinear optical properties of organic and polymeric materials hasbeen the subject of numerous symposia. The International Society forOptical Engineering (SPIE) has sponsored a number of NLO relatedsymposia, e.g. the symposium "Nonlinear Optical Properties of OrganicMaterials II" on Aug. 10-11, 1989 (SPIE Proceedings Series, Vol. 1147,1990). Similarly, the Materials Research Society has sponsored asymposium titled, "Nonlinear Optical Properties of Polymers" on Dec.1-3, 1987 (Materials Research Society Symposium Proceedings, Vol. 109,1988).

The organic based materials have a number of potential advantages overthe inorganic and semiconductor based materials. First, the organicmaterials have higher NLO activity on a molecular basis. Organiccrystals of 2-methyl-4-nitroaniline have been shown to have a highernonlinear optical activity than that of LiNbO₃. Second, the nonlinearoptical activity of the organic materials is related to the polarizationof the electronic states of the organic molecules, offering thepotential of very fast switching times in EO devices. The time responseof the system to a light field is on the order of 10 to 100femtoseconds. In contrast, a large fraction of the polarizability in theinorganic crystals is due to nuclear motions of the ions in the crystallattice, slowing the time-response of the materials. In addition, thelow dielectric constant of the organic materials (e.g. 2-5 Debye at 1MHz) compared to the inorganic materials (e.g. 30 Debye at 1 MHz)enables higher EO modulator frequencies to be achieved for a given powerconsumption. Third, the organic materials can be easily fabricated intointegrated device structures when used in polymer form.

EP 218,938 and U.S Pat. No.4,859,876 have used an approach ofincorporating NLO active molecules into amorphous polymer host matricesfor NLO media. The NLO molecules are incorporated into the host byblending. Such doped polymers have the advantages of being easilyfabricated into thin films suitable for integrated optical devices. Themedia contain organic molecules (dopants) with nonlinear opticalactivity with the advantages discussed above. These films must beoriented to achieve a non-centrosymmetric alignment of the NLOchromophores. Such alignment is usually achieved by the application ofan electric field across the film thickness while the temperature of thepolymeric blend is near its glass transition temperature (T_(g)). Thepolymer is then cooled with the field on to lock the oriented moleculesin place. EP 218,938 discloses a number of polymer host materials,including epoxies, and many types of molecules which have NLO activityincluding azo dyes such as Disperse Red 1. It is known that an NLOactive material such as azo dye Disperse Red 1,(4,-[N-ethyl-N-(2-hydroxyethyl]amino-4-nitro azobenzene), may beincorporated into a host by simply blending the azo dye in athermoplastic material such as poly(methylmethacrylate), as described inApplied Physics Letters 49(5), 4 (1986) and U.S. Pat. No. 4,859,876.

While the doped polymer approach offers some advantages over organic andinorganic crystals, the approach has a number of problems. First, thestability of the NLO activity over time of such materials has been shownto be poor. A problem associated with a polymer with NLO propertiesproduced by simply blending NLO molecules into a host polymer is thatthese polymer materials lack orientational stability. There issignificant molecular relaxation or reorientation within a short periodof time resulting in a loss of NLO properties. For example, as reportedby Hampsch et al., Macromolecules 1988, 21, 528-350, the NLO activity ofa polymer with NLO molecules blended therein decreases dramatically overa period of days at room temperature.

U.S. Pat. No. 4,792,208 discloses an article containing an NLO mediumwhich employs various sulfonyl moieties as electron acceptor moieties inpolar aligned noncentrosymmetric molecular dipoles. U.S. Pat. Nos.4,869,847 and 4,859,876 disclose the use of polycarbonate resins as thehost material for blended NLO compositions. The use of polycarbonate asa matrix for dye aggregates is disclosed by Wang, U.S. Pat. No.4,692,636.

In addition, the NLO dopants in the blending polymeric media plasticizethe polymer host matrix, lowering the polymer glass transitiontemperature (T_(g)). Lowering the polymer T_(g) has the effect oflowering the temperature stability of the electrically oriented NLOmaterial or NLO medium. Near the T_(g), segments of the polymer becomemobile and the NLO active dopant molecules which were orientedelectrically undergo orientational relaxation. Once orientationalrelaxation has occurred, the NLO medium exhibits no NLO activity.

A third problem with the doped polymers is the poor solubility of theNLO chromophore in the host matrix. Finally, the NLO chromophores tendto aggregate at relatively low doping levels (e.g. 5-20 percent w/v).Such aggregates scatter light and reduce the transparency of thewaveguides to unacceptable levels.

Another disadvantage is that the polymer employed may have a low glasstransition temperature, lack sufficient tensile strength, or otherdesirable properties for optical devices.

There is a continuing effort to develop new nonlinear optical polymerswith increased nonlinear optical susceptibilities and enhanced stabilityof nonlinear optical effects. It would be highly desirable to haveorganic polymeric materials, particularly polymeric materials based onpolycarbonate and polyestercarbonate resins, with larger second andthird order nonlinear optical properties than presently used organicelectrooptic materials.

The present invention solves the problems identified above with dopedpolymers, while maintaining the advantages listed for the doped polymersand organic based NLO materials.

It is an object of this invention to make optically transparent polymersincorporating organic molecular structures which exhibit NLO activityupon orientation. It is an additional object of this invention that thepolymers comprising the NLO medium have a relatively high glasstransition temperature. A high glass transition temperature willcorrelate with high temperature stability of the NLO medium. Theincorporation of the NLO active structures into the polymer backbone hasa number of advantages. High levels of NLO chromophore functionalizationcan be achieved without increasing the scattering losses of waveguidesfabricated from the polymer. The addition of the groups which add to theNLO activity of the polymer do not plasticize the polymer and lower thepolymer T_(g). In fact, such modifications can raise the polymer T_(g).That the NLO chromophore is inherent to the polymer backbone increasethe orientational stability of the NLO chromophores in the fabricatedNLO waveguides, reducing the temporal decay of the NLO activity withtime.

SUMMARY OF THE INVENTION

The instant invention relates to amorphous polymers which exhibit secondand/or third order nonlinear optical activity following external fieldorientation. Among these polymers are bisphenol A polycarbonate andpolyestercarbonate polymers and copolymers of bisphenol A and diols ordiacids with enhanced NLO activity. These polymers exhibit NLO activitybased on the dipolar aromatic character of the backbone of the polymer.The oriented polymeric compositions of the instant invention do notdepend upon oriented dopant molecules or large pendent chromophores asdo many prior art materials. For this reason the oriented polymericcompositions of this invention retain their NLO activity for much longertimes than prior art materials. The materials of this invention alsohave generally higher T_(g) values than plasticized prior art materials,and thus are useful in higher temperature applications than prior artmaterials.

The phrase "oriented polymeric composition" as used herein indicates apolymeric composition which has been oriented by the application of anexternal field according to the methods disclosed herein, or which hasbeen oriented by some other method, such that the polymeric compositionexhibits nonlinear optical properties. In a preferred embodiment thereis enhanced second-order nonlinear optical activity.

In one embodiment the invention is a nonlinear optical medium comprisingan oriented polymeric composition having repeating units correspondingto the formula:

    R--O--X--O

wherein R is the divalent nucleus of an aliphatic or aromatic diol and Xcorresponds to the formula: ##STR1## or a mixture thereof wherein R¹ isthe divalent nucleus of an aliphatic or aromatic dicarboxylic acid.

These NLO media exhibit unexpectedly high and persistent levels ofsecond-order NLO activity when prepared according to the procedures ofthis invention.

A preferred embodiment of the present invention relates to novelpolymeric materials particularly suited for the preparation of NLOmedia. These are a polymeric composition comprising polymers containingrecurring units corresponding to the formula

    R--O--X--O

wherein R is derived from a mixture of bisphenol A and3,3'-dinitrobisphenol A and X is a mixture of ##STR2## or mixture of##STR3## and a polymeric composition comprising polymers containingrecurring units corresponding to the formula

    R--O--X--O

wherein R is derived from a mixture of 4,4'-thiodiphenol and3,3'-dinitrobisphenol A, and X corresponds to the formula: ##STR4## or amixture thereof wherein R¹ is the divalent nucleus of an aliphatic oraromatic dicarboxylic acid.

DETAILED DESCRIPTION OF THE INVENTION

The polymers used to prepare the NLO media of this invention arepolycarbonates, prepared by the reaction of a diol with a carbonateprecursor, and polyestercarbonates, prepared by reacting a diol with acarbonate precursor and a dicarboxylic acid or a diacid halide.

The diols used to prepare the polymers for the NLO media of thisinvention can be any aliphatic, alicyclic, heterocyclic or aromaticdihydroxy compound which has two hydroxyl groups capable of reactingwith carboxylic acids and/or carbonate precursors. In general, the termsaliphatic and aromatic as used herein are meant to be inclusive ofalicyclic and heterocyclic.

Typical of some of the dihydroxy diaryl compounds that areadvantageously employed are bisphenols such asbis(4-hydroxyphenyl)methane, 1,1 -bis(4-hydroxyphenyl)-1-phenylehtane,2,2-bis(4-hydroxyphenyl)propane (also commonly known as bisphenol A),2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane,2,2-bis(4-hydroxy-3,5-dibromophenyl)propane; dihydroxyphenyl ethers suchas bis(4-hydroxyphenyl)ether, bis(3,5-dichloro-4-hydroxyphenyl)ether;dihydroxy biphenyls such as 4,4'dihydroxybiphenyl,3,3'-dichloro-4,4'-dihydroxy biphenyl,2,2',6,6'-tetrabromo-3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl;dihydroxy aryl sulfones such as bis(4-hydroxyphenyl)sulfone,bis(3,5-dimethyl-4-hydroxyphenyl)sulfone; and dihydroxy biphenylsulfides and sulfoxides such as bis(4-hydroxyphenyl)sulfide andbis(4-hydroxyphenyl)sulfoxide: or mixtures thereof.

The preferred dihydroxy diaryl compounds are the bisphenol compounds,especially the 4,4'-bisphenols optionally substituted by a halogen,nitro group, or a C₁₋₆ hydrocarbon radical and biphenyl compounds.Exemplary of such diaryl dihydroxy compounds are2,2-bis(4-hydroxyphenyl)propane,1,1-bis(4-hydroxy-phenyl)-1-phenylethane,2,2',6,6'-tetrabromo-3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl,2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane,2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 4,4'-dihydroxybiphenyl andbis(4-hydroxyphenyl)sulfide also referred to as 4,4'-thiodiphenol.

Suitable diols are aliphatic diols including straight-chain and branchedaliphatic diols such as ethylene glycol, propylene glycol, butyleneglycol, and neopentyl glycol: alicyclic diols such as trans-1,4-cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexanedimethanol, cis-1,4-cyclohexanedimethanol,trans-1,3-cyclohexanedimethanol: and alkyl-, alkoxy-, orhalogen-substituted derivatives of the above said alicyclic diols suchas trans-1,4-(1-methyl)cyclohexanediol andtrans-1,4-(1-chloro)cyclohexanediol.

Suitable aromatic diols include hydroquinone, resorcinol,2,6-naphthalenediol and 1,6-naphthalenediol. A variety of additionalaromatic diols are also available and are disclosed in U.S. Pat. Nos.2,999,835; 3,028,365 and 3,153,008, the relevant parts of which areincorporated herein by reference.

In a preferred embodiment diols suitable for use in the polymericmaterials of the present invention can be represented by the formula##STR5## wherein Y is a single bond, ##STR6## or a divalent hydrocarbylor inertly substituted hydrocarbyl of up to 15 carbon atoms: each Z isindependently selected from the group consisting of --H, --NO₂, --CI,--Br, --OCH₃, --SCH₃, --CN, --NO or a divalent hydrocarbyl or inertlysubstituted hydrocarbyl of up to 6 carbon atoms; and n is 4.

The carbonate precursor may be either a carbonyl halide, a diarylcarbonate or a bishaloformate. The carbonyl halides include carbonylbromide, carbonyl chloride and mixtures thereof. The bishaloformatessuitable for use include the bishaloformates of dihydric phenols such asbischloroformates of 2,2-bis(4-hydroxyphenyl)propane,2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane,2,2-bis(4-hydroxy-3,5-dichlorphenyl) propane, hydroquinone and the likeor bishaloformates of glycols such as ethylene glycol and the like.While all of the above described carbonate precursors are useful,carbonyl chloride, also known as phosgene, is preferred.

Suitable dicarboxylic acid compounds can be aliphatic, alicyclic,heterocyclic, aromatic, or mixtures thereof. Hydroxy acids may also beused in small quantities in the preparation of the polymers of thisinvention.

Suitable aliphatic dibasic acids are those derived from straight-chainparaffin hydrocarbons such as oxalic, malonic, dimethyl malonic,succinic, glutaric, adipic, pimelic, subaric, azelaic, and sebacic acid.Also included are the halogen-substituted aliphatic dibasic acids.Aliphatic carboxylic acids containing heteroatoms and their aliphaticchain, such as thiodiglycollic or diglycollic acid may also be used.Also useful are such unsaturated acids as maleic or fumaric.

Suitable alicyclic dicarboxylic acids includetrans-1,4-cyclohexanedicarboxylic acid, cis-1,4-cyclohexanedicarboxylicacid, and 1,3-cyclohexanedicarboxylic acids: and alkyl-, alkoxy-, orhalogen-substituted derivatives of the above said alicyclic dicarboxylicacids.

Aromatic dicarboxylic acids suitable for use in the making of polymersof the present invention include terephthalic acid,4,4'-biphenyldicarboxylic acid, 4,4'-triphenyldicarboxylic acid,2,6-naphthalenedicarboxylic acid, biphenylether-4,4'-dicarboxylic acid,diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane4,4'-dicarboxylicacid, biphenylethane-4,4'-dicarboxylic acid, isophthalic acid,biphenyl-ether-3,3'-dicarboxylic acid, diphenoxyethane-3,3'-dicarboxylicacid, biphenylethane-3,3'-dicarboxylic acid, naphthalene-1,6dicarboxylicacid and 1,5-anthraquinone-dicarboxylic acid: and alkyl-, alkoxy-,nitro-, or halogen-substituted derivatives of the above said aromaticdicarboxylic acids such as chloro terephthalic acid, dichloroterephthalic acid, bromo terephthalic acid, methyl terephthalic acid,dimethyl terephthalic acid, ethyl terephthalic acid, methoxyterephthalic acid and ethoxy terephthalic acid.

Examples of hydroxy acids are hydroxy glutaric acid, mandelic acid, thevarious isomers of hydroxy benzoic acid, hydroxy biphenyl carboxylicacid, and the like.

The mono- and diacid chloride derivatives of the above-mentioneddicarboxylic acids are also suitable for preparing the polymers of thepresent invention. Further examples of suitable dicarboxylic acidcompounds or hydroxy carboxylic acid compounds are given in U.S. Pat.Nos. 3,637,595: 3,975,487; and 4,118,372, the relevant parts of whichare herein incorporated by reference. When the diaryl dicarboxylic acidsare used in combination with other suitable dicarboxylic acids,preferred are the above-mentioned aromatic carboxylic acids.

Methods of producing polycarbonates and polyestercarbonates arewell-known in the prior art. Such methods are suitable for use informing the polymeric compositions of the present invention. Suitablemethods for preparing polycarbonate resins are set forth in U.S. Pat.Nos. 3,248,414; 3,153,008; 3,215,668; 3,187,065; 3,028,365; 2,999,846;2,964,974; 2,970,137; 1,991,273; and 2,999,835; all of which areincorporated herein by reference. Similarly, methods of producingpolyestercarbonates are known in the prior art. Exemplary of methods bywhich polyestercarbonates may be produced are those methods described inU.S. Pat. Nos. 3,169,121; 4,287,787; 4,156,069; 4,260,731; 4,330,662;4,360,656; 4,374,973; 4,255,556; 4,388,455; 4,355,150 4,194,0384,238,596 4,238,597 4,252,939; 4,369,303; and 4,105,633; and articles byKolesnikov et al. published in Vysokomol Soedin as B9, 49 (1967); A9,1012 (1967); A9, 1520 (1967); and A10, 145 (1968); all of which areincorporated herein by reference. Generally the aforementioned processesinvolve the reaction of dihydroxyl containing compounds with phosgene orother suitable carbonate precursor or with a mixture phosgene or othercarbonate precursor and a dicarboxylic acid, acid anhydride or acidhalide.

The prior art process which may be used to prepare the compositions ofthe present invention generally employ a chain stopping agent(terminator) during the polymerization step to control molecular weight.The concentration of the chain stopping agent in the reaction mixturehas a direct effect on both the molecular weight and the viscosity ofthe polycarbonate or polyestercarbonate prepared. Chain stopping agentsare monofunctional compounds which react with a carbonate precursor siteon the backbone of the polymer and by such reaction ends the propagationof the polymer at such a point. Preferable chain stopping agents includemonofunctional compounds that are reactive with the carbonate precursoremployed in forming the polycarbonate or polyestercarbonate prepared.Examples of desirable chain stopping agents include monofunctionalaromatic alcohols, thiols, and amines. Preferred chain stopping agentsare the aromatic alcohols and the aliphatic alcohols.

The polymers used in the NLO media of this invention can be fabricatedinto films using solution casting techniques known to those skilled inthe art. 5-15 weight percent of the polymer is dissolved in a volatilesolvent and passed through 0.2-1.0 μm filters to remove dust particles.The polymers can be cast from these solutions into films in a number ofways, as described in the examples below. In general, the solutions caneither be cast onto large glass plates using a "Doctor-blade" techniqueor simply poured into dishes with flat plate glass bottoms. These glassplates or dishes are then covered with other glass plates or watchglasses to reduce the evaporation rate of the solvent for optimumoptical quality of the fabricated films. The thickness of the films ismeasured using a micrometer and a typical result is a thickness of10-100 μm. Films may also be fabricated by dip-coating or spin-coatingtechniques.

The films fabricated from the polymers of this invention are oriented byelectric field poling using either parallel plate poling or coronadischarge poling techniques known to those skilled in the art. In thecase of parallel plate poling, typically a film is sandwiched betweentwo glass slabs with electrically conductive and transparentIndium-Tin-Oxide (ITO) coatings. The sandwiched film is heated to nearthe polymer T_(g) and a voltage is applied to the electrodes resultingin an electric field of 0.1-0.7 MV/cm across the film. The sample isheld for 10 minutes or more and cooled to room temperature with thefield on. In the case of corona discharge poling a similar procedure isused except the films are placed on a microscope slide on a resistivelyheated block. A tungsten wire is then positioned 1 cm above the sample.The corona poling technique is described further by M. A. Mortazavi etal., J. Opt. Soc. Am. B 6(1989).

The oriented film fabricated from the polymers of this invention can becharacterized for their NLO activity by a Maker Fringe Rotation SecondHarmonic Generation Technique which is well known to those skilled inthe art. See for example, Singer et al., Appl. Phys. Lett. 49, (1986)248-250.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following examples are give to further illustrate the invention asconstrued by the inventors. However, these examples are not to beinterpreted as limiting the scope of the invention in any way. Unlessstated otherwise, all parts and percentages are given by weight.

EXAMPLE 1

This example describes the synthesis of a bisphenol-A(BA)/3,3'-dinitrobisphenol A (DNBA) copolycarbonate having a BA/DNBAmolar ratio of 1/1.

A five-liter (L) flask equipped with a thermometer, condenser, nitrogenand phosgene inlets and a paddle was charged with 64.08 g (0.281 mole)BA, 89.31 g (0.281 mole) DNBA, 0.42 g (0.0028 mole) p-tertbutylphenol,115.6 g (1.461 mole) pyridine, and 1.4 L methylene chloride (CH₂ Cl₂).

The contents of the flask were stirred at 200 rpm under a slow nitrogenpurge and 58.6 g (0.592 mole) of phosgene was added to the flask over 38minutes while maintaining the contents of the flask at a temperaturebetween 16° C. and 25° C. After the addition of phosgene, 5 mL ofmethanol and 0.2 L of 3N hydrochloric acid were added to the contents ofthe flask. The contents of the flask were stirred for an additional 15minutes and then poured into a four liter separatory funnel. The CH₂ Cl₂phase containing the polycarbonate was separated and washed with 0.42 Lof 0.5 N hydrochloric acid.

The washed CH₂ Cl₂ phase was separated and passed through a column ofmacroporous cation ion exchange resin, and the polycarbonate was thenisolated by adding one volume of the CH₂ Cl₂ phase to 3.3 volumes hexaneand 0.67 volumes acetone in an explosion resistant blender.

The precipitated product was filtered and then dried in a vacuum oven at120° C. for 48 hours. The resulting product weighed 141.7 g, had aninherent viscosity of 0.513 dL/g as measured in CH₂ Cl₂ at 25° C. and aconcentration of 0.5 g/dL, had a glass transition temperature of 161° C.as measured by differential scanning calorimetry at a 20° C./minuteheating rate, and had a BA/DNBA molar ratio of 1/1 as determined bynuclear magnetic resonance and infrared spectroscopy.

EXAMPLE 2

This example describes the preparation of a polyestercarbonate usingbisphenol A (BA), 3,3'-dinitrobisphenol A (DNBA), terephthaloyl chlorideand phosgene and having a BA/DNBA molar ratio of 1/1 and aterephthalate/carbonate molar ratio of 1/1.

A three liter flask equipped as in the last preparation was charged with41.26 g (0.181) mole BA, 57.53 g (0.181 mole) DNBA, 74.4 g (0.941 mole)pyridine and 1 L of CH₂ CL₂. The contents of the flask were stirred at250 rpm and 36.75 g (0.181 mole) terephthaloyl chloride was added to theflask over two minutes while maintaining the temperature in the range of17° C. to 23° C. The contents of the flask were stirred an additional 10minutes, 0.54 g (.0036 mole) p-tertbutylphenol was added, and then 19.5g (0.197 mole) phosgene is added to the flask over a thirty-one minuteperiod while maintaining the temperature between 17° C. and 23° C.Following the phosgene addition, the contents of the flask were washedand the polyestercarbonate product was isolated according to theprocedures of the above-mentioned preparation.

Following vacuum oven drying, the product weighed 112.4 g, had aninherent viscosity of 0.730 dL/g, had a glass transition temperature of188° C., and had a BA/DNBA molar ratio of 1/1 and aterephthalate/carbonate molar ratio of 1/1 as determined by theanalytical procedures described hereinbefore.

EXAMPLE 3

Bisphenol A polycarbonate having an inherent viscosity of 0.514 dL/g wasprepared according to the general procedure of Example 1. 7 g of thispolymer was placed in a jar and dissolved in 70 mL of dichloromethane.The sample was placed on a shaker bath for 1 hr to facilitate thedissolution of the polymer. The solution was filtered through 8micrometer and 1.2 micrometer filters.

The polymer solution was poured into a "Doctor-blade" apparatus on an8×10×1/16 inch thick glass plate. The spacing between the "Doctor-blade"and the glass plate was 1 mm and the apparatus was drawn across theglass plate in a direction opposite the spacing leaving a flat viscousfilm. Four stacks of 2 stainless steel flat washers (1/16 inch thick)were positioned on the glass plate around the film at the corners of theplate. A second glass plate similar to the first plate was placed overthe sample on the washer stacks. The purpose of the second plate was toreduce the evaporation rate of the solvent from the cast film and tokeep dust from falling on the film as it dried. The sample was dried atroom temperature for 3 days. The films were removed from the glass plateby peeling. Addition of a drop of water to the film edge facilitated thefilm removal. The films were oven dried for 6 hrs at 100° C. and vacuumoven dried at 110° C. overnight.

A 1 inch×2 inch sample was cut from the film using a razor blade. Thethickness of the film was measured to be 42 micrometers using a MetricSystems Eng Corp thin film thickness gauge. The sample was sandwichedbetween two transparent electrodes. The electrodes were 1×3×1/8 inchglass with an electrically conductive and transparent coating ofIndium-Tin-Oxide (ITO) patterned as a strip 5/8×2.25 inches in area. Thesample was placed between two aluminum blocks on a hot plate and avoltage of 2%50 V was applied across the electrodes of the sample,yielding an applied electric field of approximately 0.607 MV/cm. Thetemperature of the sample was raised to 135° C. and maintained for 15minutes. The sample temperature was lowered to 23° C. and the voltagewas turned off.

The electrodes were removed from the sample and the sample was mountedon a rotation stage. 1064 nm light pulses from a Quanta-Ray DCR-2A Nd⁺³/Yag laser were focused onto the sample using a 20 inch focal lengthspherical lens and 532 nm light created in the sample by second harmonicgeneration was collected using a Philips XP2020Q photomultiplier tube ina refrigerated housing. The photomultiplier signal was input to aStanford Research Systems SR 250 Gated Integrator and Boxcar Averager.The signal from the 532 nm light was measured as a function of angle andthe data was iteratively fit to determine the second-order nonlinearoptical coefficient, d₃₃ using equations described in Singer et al.,Appl. Phys. Lett. 49, (1986) 248-250. A y-cut quartz crystal, d₁₁=1.2×10⁻⁹ esu, was used as a reference to obtain absolute numbers.

A d₃₃ value of 0.16×10³¹ 9 esu was obtained for the 50 micrometer thicksample assuming indices of refraction of 1.5929 and 1.5677 at 532 nm and1064 nm.

EXAMPLE 4

Bisphenol A polycarbonate with an inherent viscosity of 0.575 dL/g,prepared according to the general procedure of Example 1, wascompression molded at 260° C. into a sheet approximately 497 micrometersthick and 4×4 inches in area.

A 1×2 inch sample was cut from the sheet. The sample was sandwichedbetween electrodes and electrically oriented according to the proceduredescribed in Example 3. A film of Total Plastics #2355-2 Teflon-FEP Tapewith an adhesive backing was attached to one of the ITO glass electrodeswhich sandwiched the sample. An electric field of 0.127 MV/cm wasapplied to the sample and a maximum poling temperature of 130° C. wasused.

A d₃₃ value of 0.11×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 5

A 1×2 inch sample of LEXAN™ (General Electric Trademark) polycarbonatesheet (70 micrometers thick) was sandwiched between 5.4 mil thickpolished Al sheet electrodes and electrically oriented according to theprocedure described in Example 3 except that the sample was heated in anoven during the poling process. An electric field of 0.403 MV/cm wasapplied to the sample and a maximum poling temperature of 157° C. for 14minutes was used.

A d₃₃ value of 0.09×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 6

3.45 g of the copolycarbonate prepared in Example 1 was dissolved in 40mL of dichloromethane and placed in a sonication bath. The solution wasfiltered through 8 micron pore size and 1.2 micrometer pore sizefilters. The solution was cast into film using the "Doctor-blade"apparatus as described in Example 3 with a 500 micrometer spacing. Thefilm was dried for 2 hours in a laminar flow hood and then oven dried byraising the sample temperature from 20° C. to 166° C. and then let standin the oven with the door closed until the temperature reached 20° C.

The sample was electrically oriented according to Example 3. An electricfield of 0.395 MV/cm was applied to the sample and a maximum polingtemperature of 176° C. was used.

A d₃₃ value of 1.48×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 7

An alternating copolycarbonate was prepared by the reaction of4,4'-dihydroxybenzophenone and the bischloroformate of bisphenol A as inthe general procedure of Example 1. 10.4 g of this polymer, having aninherent viscosity of 0.591 dL/g, was dissolved in 69 mL ofdichloromethane, filtered, cast into film, and electrically orientedaccording to Example 3. An electric field of 0.331 MV/cm was applied tothe sample and a maximum poling temperature of 161° C. was used.

A d₃₃ value of 0.175×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 8

A bisphenol A/4,4'-sulfonyldiphenol (1/1) copolycarbonate having aninherent viscosity of 0.735 dL/g was prepared according to the generalprocedure of Example 1. This polymer was dissolved in dichloromethane,filtered, cast into film, and electrically oriented according to Example3. An electric field of 0.352 MV/cm was applied to the 28 micrometersample and a maximum poling temperature of 194° C. was used.

A d₃₃ value of 0.971×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 9

A bisphenol A/4,4'-thiodiphenol (1/1) copolycarbonate having an inherentviscosity of 0.538 dL/g was prepared according to the general procedureof Example 1. This polymer was dissolved in dichloromethane, andfiltered as described in Example 1. The sample was cast by pouring thecasting solution into a 2 inch diameter pipe sitting on plate glass andthen dried and electrically oriented according to Example 3 except anoven was used to heat the sample during the electrical poling process.An electric field of 0.291 MV/cm was applied to the 176 micrometer thicksample and a maximum poling temperature of 141° C. was used.

A d₃₃ value of 0.971 ×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 10

A 4,4'-thiodiphenol/3,3'-dinitrobisphenol A (1/1) copolycarbonate wasprepared according to the general procedure of Example 1. This polymerwas dissolved in 1,1,2,2-tetrachloroethane and filtered as described inExample 1. The film was cast in a plate glass bottomed evaporation dishcovered with a watch glass. The films were dried in an oven at 100° C.overnight and in a vacuum oven at 110° C. for three days. The sample waselectrically oriented as in Example 3. An electric field of 0.55 MV/cmwas applied to the 37 micrometer thick sample and a maximum polingtemperature of 140° C. was used.

A d₃₃ value of 0.58×10⁻⁹ esu was measured as described in Example 3except only two data points were used in the equations to determine thed₃₃ value. The data points were the second harmonic light intensity dataat 45 degrees for the sample and 0 degrees for the quartz referencecrystal.

EXAMPLE 11

A bisphenol A/2-nitroresorcinol(1/1) copolycarbonate having an inherentviscosity of 0.257 dL/g was prepared according to the general procedureof Example 1. The polymer was dissolved in dichloromethane, filtered,cast into film, and electrically oriented according to Example 3 exceptan oven was used to heat the sample during the poling process. Anelectric field of 0.35 MV/cm was applied to the 50 micrometer thicksample and a maximum poling temperature of 145° C. was used.

A d₃₃ value of 0.07 ×10⁻⁹ esu was measured as described in Example 10.

EXAMPLE 12

The polyestercarbonate prepared in Example 2 was dissolved indichloromethane, filtered, cast into film, and electrically orientedaccording to Example 1. An electric field of 0.34 MV/cm was applied tothe 29.8 micrometer sample and a maximum poling temperature of 190° C.was used.

A d₃₃ value of 0.93 ×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 13

A bisphenol A/3,3'dinitrobisphenol A (1/1) copolycarbonate having aninherent viscosity of 0.501 dL/g was prepared according to the generalprocedure of Example 1. The polymer was dissolved in dichloromethane andfiltered according to Example 1. A microscope slide was dipped into thebottle of polymer solution and slowly withdrawn. Polymer was removedfrom one side by dissolution in dichloromethane. The sample was airdried for 1 hr and oven dried at 110° C. for 2 hrs and vacuum oven driedfor 2 hrs at 110° C. The sample was determined to be 1.26 micrometerthick by optical transmission measurements in the 400-800 nm regionaccording to methodology described by J. C. Manifacier et al., J. Phys.E: Scientific Instruments 9 (1976) 1002-1004. The sample was placed on aheater block and oriented by corona discharge poling with an appliedvoltage of 10 KV. The current measured in series with the sample was 10microamps and the maximum temperature of poling was 162° C. The coronapoling apparatus was comprised of a Tungsten Scanning TunnelingMicroscope Tip suspended 3/4 inch above the sample heater block(3/4×3/4×2 inches). The sample rests on the heater block with the filmside up and is covered with a microscope cover slip (1×2 inch).

A d₃₃ value of 8.7×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 14

The copolycarbonate of Example 11 was dissolved in dichloromethane,filtered, and cast into a film according to Example 3. The polymer wasplaced on a microscope slide and corona poled as described in Example13. The sample was determined to be 73.5 micrometer thick as describedin Example 3. The sample was oriented by corona discharge poling with anapplied voltage of 8 KV. The technique of corona poling is familiar tothose skilled in the art, see for example R. B. Comizzoli, J.Electrochem. Soc.: Solid State Science and Technology 134 (1987),424-429. The current measured in series with the sample was 6 microampsand the maximum temperature of poling was 145° C. for 15 minutes. Thecorona poling apparatus was as described in Example 13 except no coverslip was placed over the sample.

A d₃₃ value of 0.3×10⁻⁹ esu was measured as described in Example 3.

EXAMPLE 15

The persistence of NLO activity for the copolycarbonate of Example 6 wasmeasured for a sample prepared and electrically oriented according toExample 6. The data below summarizes the results of measurements of thed₃₃ value as described in Example 3 as a function of time after poling.The sample was maintained at room temperature after poling.

    ______________________________________                                        Time (days)    d.sub.33 × 10.sup.-9 esu                                 ______________________________________                                         1             1.5                                                             26             1.05                                                           47            0.9                                                            130             0.85                                                          250            0.7                                                            300            0.8                                                            640            0.8                                                            ______________________________________                                    

The data above demonstrates the high and persistent NLO activity of thecopolycarbonate of Example 6.

What is claimed is:
 1. A polymeric composition comprising polymerscontaining recurring units corresponding to the formula:

    R--O--X--O

wherein R is derived from a mixture of bisphenol A and3,3'-dinitrobisphenol A and X is a mixture of ##STR7## or a mixture of##STR8##
 2. A polymeric composition comprising polymers containingrecurring units corresponding to the formula:

    R--O--X--O

wherein R is derived from a mixture of 4,4'-thiodiphenol and3,3'-dinitrobisphenol A, and X corresponds to the formula: ##STR9## or amixture thereof, wherein R¹ is the divalent nucleus of an aliphatic oraromatic dicarboxylic acid.